realbasic pure advection

' Sub Actionに記述した線形移流方程式
’f：スカラー量
’fn：スカラー量 (更新後)
’df/dt + u df/dx = 0
'dはパーシャルに読み替えてもらえれば。

　Dim s as string
  Dim i as integer
  dim f() as double
  dim fn() as double
  dim n As  Integer
  dim fout as FolderItem
  Dim txtout as TextOutputStream
 
  s = "Program START!"
  lbResult.AddRow(s)
  Redim f(ixmx)
  Redim fn(ixmx)
 
  For i = 1 to ixmx
    f(i) = 0.0
    fn(i) = 0.0
    If i>10 And i<20 Then
      f(i) = 1.0
      fn(i) =1.0
    end if
    s =str(i) +","+ str(f(i))
    lbResult.AddRow(s)
  next i
 
  For n=1 to 100
    for i =2 to Ixmx
      fn(i) = f(i) - u*dt/dx *(f(i) - f(i-1))
    next i
    for i = 2 to ixmx
      f(i) = fn(i)
    next i
  next n
  For i = 1 to ixmx
    s = str(i) + ","+str(f(i))
    lbResult.AddRow(s)
  next i